Protective device for a luminous diode

ABSTRACT

A luminous diode protecting device, which comprising a circuit containing a luminous diode and a means being connected with said luminous diode and being capable to keep the voltage supplied to said luminous diode in an inverse direction under the reverse withstanding voltage of said luminous diode.

O Unite States Patent 1 1111 3,795,821

Ichiyanagi Mar. 5, 1974 [54] PROTECTIVE DEVICE FOR A LUMINOUS 3,230,429 1/1966 Stehney 307/202 X DIODE 3,486,028 12/1969 Schade 2,944,165 7/1960 Stuetzer 307/311 [75] Inventor: Toshikazu Ichiyanagi, Tokyo, Japan [73] Assignee: Canon Kabushiki Kaisha, Tokyo, Primary Examiner Rudolph v. Rolinec Japan Assistant Examiner-B. P. Davis [22] Filed; Aug, 9, 1972 Attorney, Agent, or FirmToren, McGeady and [21] Appl. No.: 279,013 Stanger [30] Foreign Application Priority Data M T Au 9, 1971 Japan 46-71167 [57] ABST C A luminous diode protecting device, which comprising [52] US. Cll. 307/202, 307/311, 250/217 SS a circuit containing a luminous diode and a-means C .f being connected Said luminous diode and being [5 1 F'eld 0 Search 307/311 250/217 SS capable to keep the voltage supplied to said luminous diode in an inverse direction under the reverse with- [56] TEReferences C'ted E standing voltage of said luminous diode.

UN] D STATES PAT NTS 3,665,442 5/1972 Brooks 250/217 SS 5 Claims, 4 Drawing Figures De 'T/ B2 D R 52 1* LL S1 i l c PAIENTEDIMR 5W 55195821 SHEET 2 OF 2' Ac De 1 PROTECTIVE DEVICE FOR A LUMINOUS DIODE The present invention relates for a luminous diode.

A luminous diode is used for indication purpose in various instruments or as a head for optical recording in a video-disc. Because its reverse withstanding voltage is not sufficiently high, such luminous diode as used in a conventional manner has a shortcoming that it may be damaged when alternating current is used, or when reverse voltage is impressed by an error, or when the voltage which has been given to other circuit is momentalily impressed as reverse voltage, etc.

The present invention is to provide a protective device for a luminous diode, by which damages to a luminous diode is prevented.

Another object of th present invention is to provide a luminous diode protective device, which contains such diode as being provided in series with or in parallel with the luminous diode for preventing damages to the luminous diode.

FIG. 1 is a circuit diagram wherein the protective device shown in Example 1 of the present invention is adopted.

FIG. 2 is a circuit diagram showing Example 2 of the present invention.

FIG. 3 is a circuit diagram showing Example 3 of the present invention.

FIG. 4 is a circuit diagram showing Example 4 of the present invention.

FIG. 1 shows a case when the luminous diode protective device of the present invention is adopted in a device to drive and control a cine-camera C by a remote control unit V, and S is a release switch of a cinecamera C, and S is a release switch for a cine-camera C being provided at the remote control unit V. L is a load such as a motor, a magnet, a resistances, etc., and B is a high voltage power source of, for example, 6 volts, while B is a low voltage power source of, for example, 3 volts. D is a luminous diode which emits light by placing the switch S in on" state, and R is its load resistance. In this case the cine-camera C is controlled to a protective device by the switch S and its state is confirmed by the luminous diode D When the switch S is in off state the power source B, and the power source B are impressed on the luminous diode D through the load L and the resistance R, thus there is such possibility that the luminous diode D may be damaged, therefore a diode D is connected in parallel with the luminous diode D in a reverse polarity.

While in the Example 1 shown in FIG. 1 the diode D is connected in parallel with the diode D in an inverse direction, the diode D may be connected in series with the luminous diode D, in an ordinary direction.

Now, explanations shall be made on an example wherein a diode D is connected in series with a luminous diode D referring to FIG. 2, in which a diode D is connected in series with a luminous diode D R' is a resistor being connected in parallel with the luminous diode D Reverse voltage working on the luminous diode will flow through the diode D and a resistance R, thus the luminous diode D can escape from being damaged.

FIG. 3 shows a case wherein a luminous diode D, is used in place of the diode D in the Example 1 shown in FIG. 1. The luminous diode D, will protect the luminous diode D when reverse voltage works on the luminous diode De, and at a same time it indicates the fact that reverse voltage is working. When an alternating current power source AC is connected in place of the direct current power source B in Example 3, flashing indication can be obtained.

Example 4 of FIG. 4 shows a case when a light receiving diode PD is connected in place of the diode D in Example 1. In this Example 4 the light receiving diode PD protects the luminous diode D and at a same time receives the light emitted by the diode D and gives counter bias to the luminous diode D to turn off the same. Said counter bias is put off as the luminous diode D is turned off, then the luminous diode is lighted again. That is, it is attenuatingly oscillated. In the event it is intended to simply oscillate the same, a photoresistance element may be used in place of the light receiving diode.

Since the present invention has the above-mentioned arrangement even when reverse voltage works on the luminous diode D it is protected by the diode D, etc.

What is claimed is:

1. An apparatus for energizing and protecting a luminous diode, comprising diode means connected in parallel with said luminous diode, a resistance connected in series with said luminous diode and with said diode means, and circuit means for applying a current through said resistance and said diode means as well as said luminous diode, said diode means exhibiting a voltage drop thereacross less than the maximum inverse voltage which the luminous diode can withstand when said circuit means applies an inverse voltage across the luminous diode.

2. An apparatus as in claim 1, wherein said diode means is poled in a direction reverse to that of said luminous diode.

3. An apparatus as in claim 2, wherein said diode means is a luminous diode.

4. An apparatus as in claim 3, wherein said diode means is a light receiving diode.

5. An apparatus as in claim 4, wherein said light receiving diode receives light from said luminous diode. 

1. An apparatus for energizing and protecting a luminous diode, comprising diode means connected in parallel with said luminous diode, a resistance connected in series with said luminous diode and with said diode means, and circuit means for applying a current through said resistance and said diode means as well as said luminous diode, said diode means exhibiting a voltage drop thereacross less than the maximum inverse voltage which the luminous diode can withstand when said circuit means applies an inverse voltage across the luminous diode.
 2. An apparatus as in claim 1, wherein said diode means is poled in a direction reverse to that of said luminous diode.
 3. An apparatus as in claim 2, wherein said diode means is a luminous diode.
 4. An apparatus as in claim 3, wherein said diode means is a light receiving diode.
 5. An apparatus as in claim 4, wherein said light receiving diode receives light from said luminous diode. 